Wednesday, June 12, 2013

The right amount of SET...

In line with my New Year's Resolution - for 2013 to be the year I become proficient in saw sharpening - I have been at it again. Filing and setting lots of saws, that is.

Using a saw set takes some concentration! You've gotta be careful to set every second tooth.
Putting set on the teeth means bending each alternate tooth outwards. When this is done from each side of the saw, each tooth points the opposite direction to it's neighbours. A Saw Set is a special tool like a form of pliers designed for applying set to the teeth, pictured above. Squeezing the handle pushes a pin which bends the tooth against an anvil. The angle of the bend is determined by the adjustable anvil. You dial in the tooth spacing (in Points Per Inch) on the anvil's dial and set every second tooth. You then turn the saw around and come down the other side to set the remaining alternate teeth.

The reason for giving the teeth set is to increase the size of the kerf - the width of the wood material removed by the teeth. There are many variables here. There is a lot of science in saw construction, tooth geometry, and sharpening! However, as a general rule of thumb, a saw with no set will be inclined to jam in the wood. Too much set and the saw will easily wander all over the place and it is harder to do more accurate cuts (eg joint cutting). More set is needed with green softwoods, and less set is required for seasoned hardwoods.

Amongst the saws I have been sharpening recently, the dovetail saws need minimal set. This helps make very accurate cuts with it's very fine teeth. However I also had to sharpen the "tenon saws" (technically Sash saws) I use for kids and others in my workshops. I was preparing for another day in a school with about 110 kids, and 5 of the saws "needed a birthday". I'd noticed at the last gig that some of the saws were getting a bit dull. I remember when someone was cutting through a nail in the wood they were cutting. I heard it from across the room and went straight over. Too late! Anyway, I filed the saws sharper, but felt that not all of them required re-setting.
My two favourite saws, 14 inches long with very heavy brass backs. English made: BUCK.
Interestingly, while watching the kids at work, I noticed that my two favourite (freshly sharpened) saws were offering a little more resistance to the 5 year old kids than I like. They were good for me, as I have a nice straight relaxed sawing action. However for kids learning and sawing for the first time, it was clear that a tad more set would've been good!

Yep, it's all about the right amount of set for the array of variables on hand at the time!
Mmm ...the right amount of SET...  

No comments:

Post a Comment